(Inside MossRehab/Winter 2015) - Matching the right prosthetic device to the right patient has always been of critical importance at MossRehab, according to Alberto Esquenazi, MD, chief medical officer. And with new technologies, patients are able to do more with less effort in a safer way than ever before.
"These new devices really improve patients' functional capacity but they also increase the challenges of rehabilitation," says Dr. Esquenazi. "In the upper limb, electronics have been implemented that allow the patient to use fewer sources of control signals for a more complex device. In the past, these upper limb prosthetics were very rudimentary-you had one type of grip, a pinch, and very little control of its position, intensity or speed. They evolved to offer more degrees of freedom but still lacked proper control. Now, we can use tricks in the electronic system to command these actions, using multiple muscles or grading the amount of muscle contraction."
Andreas Kannenberg, PhD, executive medical director of Ottobock North America, says there are two exciting developments in upper limb technology. One is improvement in the functionality of prosthetic hands through introduction of the lateral grip (key grip), which researchers believe is used in up to 80 percent of grasping activities.
“It would be nice to access 40 grip types, as some of these hands have the capacity to offer, but with current mechanisms, control is too cumbersome,” says Dr. Kannenberg.
The second development is improvement of these control mechanisms.
"There is an intriguing technique which requires surgery," says Dr. Kannenberg. "It's targeted muscle reinnervation for patients with high level arm amputation. The surgeon cuts nerves that usually supply the pectoralis muscle and transfers nerve trunks from the residual limb into that chest muscle. The nerves grow into the pectoral muscle, creating several muscle sections that allow patients to activate their upper limb prosthesis using them."
This technique is already used in a small number of people in the United States, says Dr. Kannenberg, and patients have been able to open and close the hand, move a finger, and manage several other signals for simultaneous control of the prosthetic wrist, hand and elbow.
In lower limb technology, microprocessor-powered knees and ankles and passive prosthetic knees have begun to offer patients the ability to safely and intuitively walk up stairs or inclines.
"These sophisticated control mechanisms and devices are allowing patients to function in ways they couldn't in the past," says Dr. Esquenazi. "In the lower limb, we have electronics that can slow down or speed up the movement of the ankle or knee and provide assurance that the knee won't buckle during walking on uneven terrains, which used to happen with mechanical devices. It's really important that patients have control over these devices. You wouldn't want an automatic leg. You want it to do what you want to do, just as with the grip strength and speed for the upper limb."
These new devices require an individualized therapeutic approach from clinicians involved in a patient’s rehabilitation.
"The new technologies require that you understand how they work, what specific features they have and how you can train your patient to take full advantage of functions of their particular prosthetic components," says MossRehab physical therapist Maria Lucas, PT, DPT, amputation program coordinator. "Therapists must keep up to date on new features and abilities. The way I would teach a person with one type of limb to walk down steps is different with a different prosthetic knee."
As these technologies are improving, Lucas says therapist and patient education are key to achieving the best outcomes.
“We can rely on our colleagues, specifically the prosthetists and prosthetic manufacturers, to help us understand the latest features of these devices,” says Lucas. “Once we know how it functions, we can teach our patient to take advantage of it.”
Lucas says that while technology is a wonderful thing, it’s not the answer to every obstacle people with amputation face.
"They still need to have range of motion, strength, coordination, endurance, cognition and balance to get the benefits from these technologies," says Lucas. "There is an increasing need for all clinicians to understand what particular groups of patients' problems can be solved with technology and what types of problems require a therapeutic approach. Technology is only part of the process of rehabilitation."
Achieving the Right Fit Can Be a Challenge
Both Lucas and Dr. Esquenazi say one of the biggest challenges surrounding these new prostheses is the hype caused by the news media and the internet.
"We see young, very fit, healthy patients doing amazing things with the technology available to them, and that's great," says Lucas. "But most people who lose limbs do so because of chronic diseases. While I fully believe technology also helps people with amputation due to disease, technology alone is not the answer to getting them back to function and a rewarding lifestyle. They need psychological support, therapy and training provided by a highly experienced staff like the one at MossRehab, where we deal with several hundred new patients a year."
Dr. Esquenazi say it’s critical to match a patient’s device to his or her reality.
"We need to be careful not to under- or over-prescribe," says Dr. Esquenazi. "It's most important to consider the functional level of a patient and if a certain device can provide additional function and safety. Patients want what they see on TV, but we need to explain why we're opting for something different. We also need to support the medical necessity for the device we prescribe or insurance won't cover it."
Dr. Esquenazi explains that prostheses—especially the newest and most advanced versions—are more costly, and patients often experience sticker shock when they find out what insurance will cover and what the balance is that they’ll need to pay.
"It is my responsibility, as their physiatrist, to prescribe the right device for the patient and stand behind this medical decision," he says. "This comes from a team approach that includes the prosthetist, therapists, physician and patient."
And that team must consider other elements beyond the devices.
"As these prostheses become more sophisticated, they require batteries and electronics," he says. "One of the major concerns is that, with this, they get heavier and more difficult for the patient to carry. We need to make sure a patient's device is as comfortable and functional as possible while still matching up with his or her demands."